Do not unnecessarily switch NetCDF files to data mode.

src/stream_cdf_o.c

@@ -236,7 +236,13 @@ cdfDefTrajLatLon(stream_t *streamptr, int gridID, int gridIndex, const struct cd
     {
       int dimNcID = streamptr->basetime.ncvarid;
       const int fileID = streamptr->fileID;
-      if (streamptr->ncmode == 2) cdf_redef(fileID);
+      bool switch2Data = false;
+      if (streamptr->ncmode == 2)
+        {
+          cdf_redef(fileID);
+          switch2Data = true;
+          streamptr->ncmode = 1;
+        }
 
       char axisname[CDI_MAX_NAME];
       const int axistype = (inqs->axisSym == 'X') ? CDI_XAXIS : CDI_YAXIS;
@@ -244,8 +250,11 @@ cdfDefTrajLatLon(stream_t *streamptr, int gridID, int gridIndex, const struct cd
       cdiInqKeyString(gridID, axistype, CDI_KEY_NAME, axisname, &length);
       cdf_def_var(fileID, axisname, xtype, 1, &dimNcID, &ncvarid);
       cdfPutGridStdAtts(fileID, ncvarid, gridID, inqs->axisSym);
-      cdf_enddef(fileID);
-      streamptr->ncmode = 2;
+      if (switch2Data)
+        {
+          cdf_enddef(fileID);
+          streamptr->ncmode = 2;
+        }
     }
 
   ncgrid[gridIndex].gridID = gridID;